To express \( \log_{2} 9 \) as a quotient of two common logarithms, we can use the change of base formula which states:
\[ \log_{b} a = \frac{\log_{k} a}{\log_{k} b} \]
for any base \( k \). We can choose \( k = 10 \) (common logarithm) to write:
\[ \log_{2} 9 = \frac{\log 9}{\log 2} \]
Thus, the answer is:
- \(\frac{\log 9}{\log 2}\)